1. Field of the Invention
The invention relates to an optical switch and, in particular, to an optical switch using reflective elements disposed in parallel to switch optical paths.
2. Description of the Related Art
In a currently used optical switch, a number of mirrors are used to change the optical paths of incident light and are shifted for switching light outputs at different output ends. FIGS. 1A and 1B show two different states of this optical switch, respectively. In FIGS. 1A and 1B, a collimator 11 and a collimator 13 serve as input ends, and a collimator 12 and a collimator 14 serve as output ends.
Referring to FIG. 1A, in a conventional optical switch 1, the collimators 11 and 13 receive a first ray R1 and a second ray R2, respectively. The first ray R1 is output from the collimator 12 after reflected by the mirrors 101 and 102. The second ray R2 is output from the collimator 14 after reflected by the mirrors 103 and 104.
Referring to FIG. 1B, if the mirrors 102 and 103 are shifted for changing the state of the optical switch 1, the optical paths of the first ray R1 and the second ray R2 are changed. After positions of the mirrors 102 and 103 are changed, the first ray R1 is output from the collimator 14 after reflected by the mirrors 101 and 104. On the other hand, the second ray R2 is output from the collimator 12 after reflected by the mirrors 103 and 102. The optical switch 1 can switch output ray to the desired collimator by way of shifting the mirror.
One drawback of the above-mentioned optical switch is that the manufacturing cost is relatively high. First, when the mirrors are shifted for switching, any errors in the positioning of the mirrors will affect the optical path; therefore the error control has to be relatively accurate so as not to adversely influence the switching effect. In addition, since the positioning accuracy of each mirror may greatly influence the alignment of each collimator during the assembling process, the position of each mirror must be relatively accurate. Due to the above-mentioned factors and the fact that there are a great many mirrors used in the optical switch, the manufacturing cost of such an optical switch is relatively high.
In addition, the example stated above is only a 2xc3x972 optical switch. If the number of input ends or output ends is increased, such as a 3xc3x973 optical switch or larger, a greater number of mirrors must be used. In this case, the difficulties of manufacturing and assembling these devices are significantly increased with an increase in the number of input ends or output ends, and the manufacturing cost is also greatly increased.
In view of the above-mentioned problems, it is an important object of the invention to provide an optical switch capable of decreasing the number of used elements.
Another object of the invention is to provide an optical switch capable of decreasing the difficulty of alignment in the manufacturing process.
To achieve the above-mentioned objects, an optical switch in accordance with the invention includes at least one input end, at least one output end, a reflective device and a switching device. The reflective device includes at least one flat glass and at least one reflective element provided on the flat glass. The switching device switches the position where the ray enters the reflective device and transmits the ray to selectively output from one of the output ends after the ray is reflected by the reflective element.
The reflective element can be a reflective film coated or attached on the flat glass. The flat glass has two parallel optical planes, and the reflective element is coated or attached on one of the optical planes.
When there are a plurality of reflective elements, the reflective element is disposed in the reflective device such that the reflective device has a plurality of reflective regions. When entering different reflective regions, the rays are output from different output ends.
The switching device can be a linear driving device for moving the reflective device. The linear driving device moves the reflective device closer to or away from the input end, or in a direction perpendicular to a plane containing the optical paths.
The switching device can also include a rotatable flat glass disposed between the input end and the reflective device. The rotatable flat glass is rotated to change a deflection offset ofr the ray after being refracted so as to change the position where the ray enters the reflective device.